Question

what is responsible for making an axle spin in an electric motor?
○ an outside power source attached to a magnet
○ an outside power source attached directly to the axle
○ an electric current passing through an armature that lies in a magnetic field
○ a magnetic field inducing a current in an armature that lies in a magnetic field

Explanation:

To determine what makes an axle spin in an electric motor, we analyze each option:

• Option 1: Attaching a power source to a magnet doesn't directly make the axle spin.
• Option 2: Attaching a power source directly to the axle won't create the necessary force for rotation.
• Option 3: In an electric motor, an electric current passes through the armature (which is in a magnetic field). The interaction between the current - carrying armature and the magnetic field produces a torque, causing the axle (connected to the armature) to spin.
• Option 4: This describes electromagnetic induction (used in generators), not the operation of an electric motor.

Answer:

C. an electric current passing through an armature that lies in a magnetic field